JP2002115034A - Nonoriented silicon steel sheet, stock for cold rolling therefor and its production method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stock for cold rolling, giving a nonoriented silicon steel sheet having excellent magnetic properties and surface properties, and to provide its production method. SOLUTION: This nonoriented silicon steel sheet has a composition containing, by mass, <=0.005% C, [Si(%)+Al(%)+0.5Mn(%)]: 0.1 to 3.0%, <=0.20% P, <=0.030% S and <=0.0050% N, and the blance substantially Fe, in which the product of the mass fraction of Fe and the density of the steel is >=7.40, and also, the accumulated degree of the [200] plane in the central part of the sheet thickness is >=1.10 by random ratio. Further, in the stock for cold rolling of the nonoriented silicon steel sheet, the accumulated degree of the [200] plane in the central part of the sheet thickness is >=6.0 by random ratio. The steel sheet is produced by subjecting a slab having the above chemical composition to hot rolling, performing rolling at a draft of 4 to 15% or cold working by tensile bending at an elongation percentage of 0.5 to 3% and annealing into the stock for cold rolling and subjecting the stock to cold rolling and finish annealing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a non-oriented electrical steel sheet having excellent magnetic properties and good surface properties, a material for cold rolling the same, and a method for producing the above-mentioned non-oriented electrical steel sheet.

[0002]

2. Description of the Related Art In recent years, efforts to save energy have become more active due to global environmental problems and the like. In response to these trends, the miniaturization and high efficiency of electrical equipment are being promoted, and there is a need to improve the magnetic properties of non-oriented electrical steel sheets that are widely used as core materials for motors, transformers, etc. Have been.

A non-oriented electrical steel sheet is prepared by hot rolling a steel having a predetermined chemical composition into a hot-rolled sheet, cold-rolling the sheet into a cold-rolled sheet having a thickness of a final product, and finishing annealing. To produce a steel sheet (final product) having desired magnetic properties.

In order to improve the magnetic properties, it is known that it is better to increase the crystal grain size of a steel sheet before cold-rolling to the thickness of the final product (hereinafter, referred to as “material for cold rolling”). As a method thereof, there is a method of annealing a hot-rolled sheet before cold rolling (hereinafter, this annealing is simply referred to as “hot-rolled sheet annealing”).

[0005] However, there is a limit to the improvement of the magnetic properties only by annealing the hot-rolled sheet, and there is a problem that if the crystal grains of the hot-rolled sheet are excessively coarsened, the surface properties of the product are deteriorated. As means for solving this, Japanese Patent Laid-Open Publication No.
No. 3, JP-A-1-309921, and JP-A-5-171280 disclose that a hot-rolled sheet is subjected to cold rolling at a low rolling reduction and then annealed to obtain a crystal grain of a material for cold rolling. Has been proposed, and then finish annealing is performed by cold rolling to a final product thickness.

However, these methods focus on only the coarsening of the crystal grain size of the material for cold rolling, as in the hot-rolled sheet annealing method. Deterioration of the surface properties was unavoidable, and the effect of improving the magnetic properties obtained was limited.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of these problems.
An object of the present invention is to provide a non-oriented electrical steel sheet having excellent magnetic properties and surface properties, a material for cold rolling of a non-oriented electrical steel sheet suitable for the production thereof, and a method for producing the non-oriented electrical steel sheet.

[0008]

[Means for Solving the Problems] [1]
The [00] plane has two easy magnetization directions in the plane, and the [110] plane has 1
Have one. Therefore, in order to increase the magnetic flux density of the non-oriented electrical steel sheet, in the crystal texture of the product steel sheet, the degree of integration of the [100] or [110] plane parallel to the steel sheet plane is increased, and the direction of easy magnetization is It is known that it is better to reduce the degree of integration of the [111] plane. Usually, the [111] plane is strongly accumulated in the central part of the sheet thickness, and this is a major factor that hinders the improvement of the magnetic properties of the steel sheet. Therefore, the magnetic properties of the non-oriented electrical steel sheet are parallel to the steel sheet plane at the center of the thickness of the final product [20
0] It can be improved by increasing the degree of integration of the plane (hereinafter simply referred to as “[200] plane integration degree)”. As is well known, the [200] plane integration corresponds to the [100] plane integration.

From such a viewpoint, the present inventors have focused on the importance of texture control in improving the magnetic properties of non-oriented electrical steel sheets and affect the degree of [200] plane integration at the center of the sheet thickness of the final product. The following experiment was performed to clarify the factors.

A. C: 0.0031%, Si: 0.4% by mass (hereinafter, the chemical composition in% means mass%).
6%, Mn: 0.18%, P: 0.074%, S: 0.
015, steel containing sol. Al: 0.0002%
It is heated to 50 ° C and hot rolled to finish at 850 ° C to obtain a hot-rolled sheet having a thickness of 2.3 mm, which is subjected to cold-working at various working degrees and annealing at various temperatures to be used for cold-rolling. I got the material. These cold rolled materials were cold-rolled into steel sheets having a thickness of 0.5 mm, and subjected to continuous annealing at 850 ° C. for 30 seconds as finish annealing.

[0011] An X-ray diffraction test was performed on the cold rolled material obtained in the above experiment and the steel sheet (final product) after continuous annealing, and an X-ray diffraction test was performed. Is calculated as a ratio (I / I) between the X-ray integrated intensity (I) of the [200] plane and the X-ray integrated intensity (I ₀ ) of the sample whose accumulation status is random.
I ₀ ; hereinafter simply referred to as “random ratio”).

FIG. 1 shows the cold rolled material obtained in the above experiment.
9 is a graph showing the relationship between the [200] plane integration degree and the [200] plane integration degree of the final product. As shown in FIG. 1, [20]
0] There is an extremely good correlation between the degree of surface integration and that of the final product. If the surface integration at the center of the sheet thickness of the cold-rolling material is high, the surface is cold-rolled and finish-annealed. In the final product obtained as a result, the [200] plane, that is, the [100] plane remains strongly and the magnetic properties are improved.

The conventional method of merely increasing the crystal grain size of the material for cold rolling does not provide the effect of increasing the degree of [200] plane integration. Conventional cold rolling materials
[200] The degree of surface integration is less than 6 at random ratio,
[200] The degree of surface integration is at most about 1.0 or less at random ratio.

FIG. 2 is a pole figure showing the texture of the central part of the thickness of the cold-rolled material. FIG. 2 (a) shows a hot-rolled steel sheet as it is, and FIG. 2 (b) shows a hot-rolled steel sheet. The present invention relates to a steel sheet subjected to cold working and then annealed. As shown in FIG. 2B, in the steel sheet annealed after the cold working, [100] <01 is compared with the steel sheet in which the hot-rolled sheet is annealed as it is (FIG. 2A).
1> The direction is strongly accumulated. From this fact, a state where the degree of [200] plane integration at the center of the sheet thickness of the cold rolling material, that is, a state where the [100] plane integration is high, corresponds to a state where the degree of integration in the [100] <011> orientation is high. You can see that.

[100] The <011> orientation is a crystal orientation that is difficult to recrystallize. Usually, in the cold rolling-finishing process,
Silkworms are eaten in the [111] orientation that is easy to recrystallize. However, as the results of this experiment show, [100] <011
> By increasing the degree of orientation accumulation, the finish annealing
[111] Orientation development was suppressed and the material for cold rolling had
[100] <011> The orientation remains in the final product, and the magnetic properties of the final product are improved. Such a finding was not found in the conventional method of simply increasing the crystal grain size before cold rolling.

B. The present inventor further studied a method of increasing the degree of [200] plane integration at the center of the sheet thickness of the above-mentioned cold rolling material. That is, the hot rolled sheet described in the above section a was subjected to cold rolling at various rolling reductions, and the [200] plane integration degree at the center of the sheet thickness of the annealed steel sheet maintained at 750 ° C. for 10 hours was investigated. .

FIG. 3 shows [2] of the material for cold rolling obtained in the above experiment.
00 is a graph showing the relationship between the degree of surface integration and the degree of cold working. As shown in FIG. 3, the degree of integration of the [200] plane in the center of the thickness of the sheet obtained by subjecting the hot-rolled sheet to cold working and annealing is increased at a specific cold working degree. This phenomenon was also observed when cold working was performed by tensile bending deformation. From these facts, it was found that by performing appropriate cold working and then annealing, it is possible to develop the [200] texture in the central part of the sheet thickness of the material for cold rolling.

The development of the texture proceeds with the grain growth in the central part of the sheet thickness. However, when the crystal grains become excessively coarse as in the abnormal grain growth, [100] <011 in the central part of the sheet thickness is obtained. > Desired texture cannot be obtained because oriented grains are eaten by abnormal grains. In the present invention, in order to increase the degree of integration of the [100] <011> orientation of the material for cold rolling, the material is manufactured under conditions that do not cause coarsening of crystal grains. If such a material for cold rolling is used, there is no possibility that defects that have occurred in the conventional method, such as unevenness defects in the final product due to coarse grains, will occur.

C. Non-oriented electrical steel sheets have the effect of increasing the specific resistance of steel to reduce iron loss, Si, Al, Mn.
And so on. However, even if the steel has the same specific resistance and the same texture, the magnetic properties, particularly the magnetic flux density, may differ depending on the content of these alloying elements. The present inventor has conducted the following experiments in order to clarify factors other than the specific resistance and the texture that affect such magnetic characteristics.

Various steels having different contents of Si, Al and Mn are hot-rolled, cold-rolled to a rolling reduction of 8%, and then annealed at 800 ° C. for 10 hours for cold rolling. The material is cold rolled to a thickness of 0.30
mm cold-rolled sheet, and then subjected to finish annealing to obtain a final product. The texture and the magnetic flux density B ₅₀ of the obtained final product were measured. As a result, the textures were almost the same, but the magnetic flux densities were different.

The present inventor believes that this difference in magnetic flux density is caused by the difference in saturation magnetic flux density of the steel sheet, and thus the magnetic characteristics and the number of Fe atoms per unit volume (hereinafter, also simply referred to as “Fe atom density”). The relationship with was analyzed.

The saturation magnetic flux density is expressed as a sum of magnetic moments of Fe atoms contained in a unit volume. That is, the saturation magnetic flux density is proportional to the Fe atom density, and the Fe atom density is equal to the product of the total number of atoms per unit volume and the atomic fraction of Fe.

The total number of atoms per unit volume may be obtained by dividing the mass (density) per unit volume by the mass of an atom, and the mass of the atom may be obtained by dividing the atomic weight by the Avogadro number. From these facts, the total number of atoms per unit volume is a value obtained by dividing the product of the density and the Avogadro number by the atomic weight. In the case of an alloy such as steel, an average atomic weight calculated from the atomic weights and atomic fractions of the constituent elements may be used as the atomic weight.

The atomic fraction of Fe can be converted from mass%. By the conversion of atomic% and mass%, the term of the average atomic weight is offset, and the number of Fe atoms per unit volume, F
The e atomic density is proportional to the product of the steel density and the mass fraction of Fe (hereinafter, this product is also referred to as “Fe ^* ”).
Here, the “mass fraction of Fe” referred to in the present invention is C, Si,
It means a value obtained by subtracting the mass fraction (1/100 of the content in%) of each element of Al, Mn, P, S and N from 1.

FIG. 4 shows the magnetic flux density B ₅₀ (5000A) of the final product obtained as a result of the above investigation and having a similar texture.
/ M is a graph showing the relationship between the magnetic flux density in a magnetic field and each Fe ^* . As shown in FIG. 4, if the texture is the same, there is a good correlation between the magnetic flux density B ₅₀ and Fe ^*, the magnetic flux density B ₅₀ as Fe ^* is larger the better.

To increase Fe ^* , the content of the alloying element may be suppressed. However, in order to reduce iron loss, it is necessary to contain the alloying element to some extent in order to obtain a desired specific resistance. Therefore, in order to increase Fe ^* after obtaining a desired specific resistance, it is necessary to consider the influence of alloying elements on the density of steel in consideration of Si.
, Al, Mn, etc. may be determined.

The present invention has been completed on the basis of these new findings. The gist of the present invention is as follows: a non-oriented electrical steel sheet described in (1) and (2) below; A material for rolling and a method for producing the material according to (4).

(1) Chemical composition in mass%, C: 0.00
5% or less, Si equivalent represented by the following formula is 0.1% or more,
One or two or more of the group consisting of Si, Al and Mn are contained in an amount of 3.0% or less, and S: 0.030
% Or less, N: 0.0050% or less, and the balance is substantially Fe
And the product of the mass fraction of Fe and the density of steel is 7.40.
Non-oriented electrical steel sheet characterized in that the degree of integration of the [200] plane in the central part of the sheet thickness is 1.10 or more at a random ratio; Si equivalent = Si (%) + Al (%) + 0. 5Mn (%).

(2) The non-oriented electrical steel sheet according to (1), wherein the chemical composition further contains P: 0.05 to 0.20% by mass. (3) having the chemical composition according to the above (1) or (2),
Non-directionality characterized in that the product of the mass fraction of Fe and the density of steel is 7.40 or more, and the degree of integration of the [200] plane in the center of the sheet thickness is 6.0 or more in a random ratio. Material for cold rolling of magnetic steel sheet; Si equivalent = Si (%) + Al (%) + 0.5Mn (%).

(4) Having the chemical composition described in (1) or (2) above, the product of the mass fraction of Fe and the density of steel is 7.4.
Hot rolling is performed on a slab of 0 or more, and the obtained hot rolled sheet is rolled with a rolling reduction of 4 to 15% or an elongation is 0.1%.
A method for producing a non-oriented electrical steel sheet, comprising: performing cold working by 5% to 3% tensile bending, and then performing annealing to obtain a material for cold rolling, and performing cold rolling and finish annealing on the material.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described in detail. Chemical composition of steel; C: Residual in the final product causes magnetic aging and adversely affects iron loss. Particularly, in order to suppress magnetic aging, the C content is set to 0.005% or less. Si, Al which is preferably 0.003% or less
And Mn: These elements all have the effect of increasing the specific resistance of steel, reducing eddy current loss and reducing iron loss.
As a result of investigating the effect of each element on the increase in specific resistance of steel, Al was about the same as Si, and Mn was about 1/2 of Si. Therefore, it is reasonable to consider the influence of these elements on iron loss reduction as a total amount represented by {Si (%) + Al (%) + 0.5Mn (%)} (hereinafter, the above total amount is referred to as “Si Equivalent ”).

In order to obtain an iron loss reducing effect, the Si equivalent of steel is set to 0.1% or more. Preferably it is 0.2% or more, more preferably 0.5% or more. If the Si equivalent exceeds 3.0%, the magnetic properties deteriorate due to the decrease in the number of Fe atoms, as described later. Further, the hardness of the steel sheet may become excessively high, the punching property may be reduced, and the productivity of the iron core manufacturing process may be significantly reduced. To avoid these inconveniences, S
i The equivalent is 3.0% or less. When the magnetic flux density is particularly increased, the Si equivalent is desirably low, preferably 1.5% or less.

In the present invention, Si, Al and Mn are used.
One or two or more of the group consisting of are contained so that the Si equivalent is within the above range. The upper limit of the content of each element is as follows: Si is 3.0% or less, Al is 3.0% or less, and Mn is 6.0% or less. The Mn content is preferably set to 3% or less because the transformation point decreases as the Mn content increases, and the α-γ transformation may occur during the finish annealing.

If Al forms fine nitrides in the steel, it may hinder the growth of crystal grains during annealing and may hinder the improvement of iron loss. To avoid this, the Al content should be 0.002%
It is desirable that the content be not more than 0.15% within the above range.

P: P has little effect on magnetic properties and is not an essential element. However, P is effective in increasing the hardness for improving the punchability of steel. Therefore, P may be contained for the purpose of adjusting the hardness. In that case, in order to obtain a desired effect, it is preferable to contain P by 0.05% or more. If P is excessively contained, the steel becomes brittle, and the sheet may be broken during cold rolling. Therefore, in order to avoid this, even when P is contained, the content is preferably 0.20% or less.

S: S forms a sulfide in the steel and impairs the magnetic properties. N: N has a function of forming fine nitrides, inhibiting the growth of crystal grains and deteriorating magnetic properties.

The balance is substantially Fe. Substantially, the inclusion of Sb, Sn or B in steel has the effect of suppressing the development of the [111] orientation during texture formation and improving the magnetic flux density of the final product. Therefore, particularly when it is desired to improve the magnetic flux density, it means that one or more of these elements may be contained. In that case, the content is as follows: Sb: 0.01% or more, 0.3% or less, Sn: 0.
01% or more, 0.3% or less, B: 0.0005% or more,
It is desirable that the content be 0.01% or less.

The product of the steel density and the mass fraction of Fe (F
e ^* ); A higher magnetic flux density is obtained as the Fe atom density is higher. When alloying elements are included to reduce iron loss, in order to avoid a remarkable decrease in magnetic flux density, the product of the steel density and the mass fraction of Fe, which is a numerical value proportional to the Fe atomic density (F
e ^* ) is equal to or greater than 7.40. When particularly excellent magnetic flux density is required, Fe ^* is preferably 7.6 or more. The Fe ^* of the steel can be calculated by obtaining the density of the steel from the weight in air and water, and obtaining the mass fraction of Fe from the chemical composition of the steel.

For the chemical composition of the steel, the contents of elements such as C, Si, Al, and Mn are adjusted so that Fe ^* is equal to or more than the above limit value. Specifically, to increase Fe ^* , reduce the Al content, which has a large effect of reducing the density of steel,
By increasing the content of Si, Mn, etc., Fe ^* can be increased even with the same specific resistance.

Texture: [200] in the center of the thickness of the final product
The degree of surface integration is set to 1.10 or more in a random ratio in order to obtain good magnetic characteristics. Preferably it is 1.20 or more.

There is a good relationship between the [200] plane integration degree of the material for cold rolling and the [200] plane integration degree of the final product manufactured by cold rolling and finish annealing the material. This degree of integration
[100] <011> Corresponds to the degree of integration of the orientation. If the degree of [200] plane integration at the center of the sheet thickness of the cold rolling material is 6.0 or more at a random ratio, the degree of [200] plane integration at the center of the sheet thickness of the final product is 1.10 or more at a random ratio. The effect of improving the magnetic properties of the final product can be obtained. Therefore, the random ratio of the [200] plane at the center of the sheet thickness of the material for cold rolling is preferably set to 6.0 or more. More preferably, it is 7.0 or more. [200] The upper limit is not particularly defined because the higher the surface integration degree, the better the magnetic properties.

The texture at the center of the sheet thickness is obtained, for example, by removing one side of the steel sheet to the center of the sheet thickness by a method such as chemical polishing to obtain a sample having the center of the sheet thickness as a measurement surface, and subjecting it to X-ray diffraction. It is measured in such a way. The random ratio is determined using the measured value and the integrated X-ray intensity of the [200] plane of the material having no orientation.

The material for cold rolling optimizes the crystal texture and has a large number of Fe atoms per unit volume. Therefore, compared to the conventional method, it is possible to provide excellent magnetic properties without making the crystal grains of the cold-rolling material so large, so that the surface of the product steel sheet due to the coarse crystal grains of the cold-rolling material can be provided. It is possible to easily produce a non-oriented electrical steel sheet having good surface properties and excellent magnetic properties without causing a possibility of occurrence of a concavo-convex defect. The crystal grain size of the material for cold rolling is
Although not particularly limited, in order to improve the surface properties, the average particle size is preferably 150 μm or less.

Production method: The non-oriented electrical steel sheet of the present invention comprises:
It is preferable to produce by the method described below. The steel having the chemical composition described in the above (1) or (2) is melted by a known method such as a converter or an electric furnace, and if necessary, subjected to a treatment such as vacuum degassing, and then subjected to continuous casting or It is made into a slab by a method such as a steel ingot and slab rolling.

The slab is hot-rolled by a known method,
It is descaled by a known method such as pickling to obtain a hot rolled sheet. The hot rolling conditions are not particularly specified, but are set to 700 to 950 ° C. in order to increase the [200] plane integration during annealing after cold working.
It is preferable to perform finish rolling and wind at 700 ° C. or less.

The hot-rolled sheet has a [1] at the center of the sheet thickness of the cold-rolling material.
[0000] In order to increase the degree of texture accumulation, light cold working and annealing are performed. The cold working is preferably performed by a cold rolling method or a tension bending method.

In the case of performing cold rolling, the rolling reduction is preferably in the range of 4% to 15%. If it is less than 4%, processing strain at the center of the sheet thickness is insufficient, and abnormal grain growth occurs at the surface layer because the strain cannot be uniformly applied in the thickness direction. [100]
The texture is not sufficiently developed and the [200] plane accumulation does not increase. In order to obtain a good degree of integration, the rolling reduction is more preferably 5% or more.

If the rolling reduction exceeds 15%, it becomes the same as ordinary cold rolling, and the [100] texture in the central part of the sheet thickness may be eroded by crystal grains of another orientation during the next annealing. .
In order to prevent this, the rolling reduction is preferably set to 15% or less.
It is more preferably at most 12%.

In the case where the cold working is performed by a tension bending method, it is preferable to provide a work having an elongation of 0.5% or more and 3.0% or less. When the elongation is less than 0.5%, the driving force for increasing the [100] texture is insufficient.

As the tension bending means, it is preferable to use, for example, a tension leveler provided in an pickling apparatus because of its excellent economic efficiency. However, the elongation percentage that can be industrially provided by these methods is limited to 3%,
It is difficult to perform further processing because the load on the equipment becomes excessive. Therefore, the elongation percentage in the case of the tensile bending method is preferably set to 3.0% or less.

It is not clear why the tensile bending method produces the same effect as the cold rolling method at a small working ratio, but it is considered that, unlike the cold rolling method, the effect of tension is large in the deformation mode. Cold bending is a type of tension bending that can be performed using a tension leveler installed in pickling equipment, etc., rather than a cold rolling method that requires large-scale cold rolling equipment to reduce manufacturing costs. Processing methods are preferred.

Annealing: Annealing is performed after cold working in order to make the [200] plane integration degree at the center of the sheet thickness of the cold rolling material 6.0 or more at a random ratio. As described above, since the [100] texture develops along with the growth of crystal grains in the central part of the sheet thickness, in order to stably obtain a desired degree of integration, the annealing temperature must be 650 ° C. or more and 87 ° C.
It is preferable to perform box annealing at 5 ° C. or less. If the annealing temperature is lower than 650 ° C., the degree of [200] plane integration is not sufficiently improved. If the annealing temperature is higher than 875 ° C., coarse grains may be generated. The reason for this is that economic efficiency is lacking due to saturation. The annealing time may be 2 hours or more. Long-time annealing exceeding 24 hours is not economical because the effect is saturated. Other annealing conditions are optional.

The above-mentioned material for cold rolling is cold-rolled to a final product thickness by a known method, and finish-annealed by a known method. The thickness of the material for cold rolling may be determined arbitrarily according to the thickness of the final product and the like.
In the case of the range of 6 mm, the thickness of the material for cold rolling is 1.
What is necessary is just to make it the range of 5-2.5 mm.

The finish annealing may be performed under the condition that recrystallization proceeds sufficiently and crystal grains grow moderately. The method may be a publicly known method, for example, a continuous annealing method, a method in which an annealing temperature is selected in a range of 650 to 1150 ° C., and the temperature is soaked for 10 seconds or more is good. The finish annealing may be decarburization annealing or annealing in a non-decarburization atmosphere. After the finish annealing, if necessary, a thin film may be applied and baked on the surface for the purpose of insulation, rust prevention, and improvement in punching workability.

By using the above-mentioned cold rolling material, it is possible to easily produce a non-oriented electrical steel sheet having good surface properties and excellent magnetic properties as compared with the case where a conventional cold rolling material is used. it can.

[0056]

EXAMPLES Steel having various chemical compositions is melted in a converter,
After adjusting the components by vacuum processing, it is continuously cast into a slab,
This was heated to 1150 ° C. and hot-rolled at a finishing temperature of 890 ° C. to obtain a hot-rolled sheet having a thickness of 2.3 mm. The winding temperature was 600 ° C.

The hot-rolled sheet is pickled, cold-rolled at various rolling reductions, or subjected to tensile bending deformation with a tension leveler at various elongation rates, and then subjected to a hot rolling at various temperatures.
Box annealing was performed for 0 hour to obtain a material for cold rolling. These cold rolling materials have a thickness of 0.50 mm or 0.30 mm.
The sheet was cold-rolled into a cold-rolled sheet having a thickness of 1 mm and subjected to continuous annealing at 850 ° C., 900 ° C. or 1000 ° C. for 0.5 minute each.

The random ratio of the [200] plane at the center of the sheet thickness of the material for cold rolling was measured by the X-ray diffraction method. The magnetic properties of the final product were determined by punching strip-shaped Epstein test pieces from the rolling direction and the width direction, and using the punched test pieces.
It measured according to the method prescribed | regulated to S-C2550.

The mass fraction of Fe was calculated from the chemical composition, the density of the steel was obtained from the weight of the steel sheet in the air and in water, and the product of these was calculated to obtain Fe ^* . Table 1 shows the chemical composition of the steel. Table 2 also shows the respective manufacturing conditions and the measurement results obtained.

[0060]

[Table 1]

[0061]

[Table 2] In Table 1, steels 7 to 10 are Fe ^* , Si equivalent, S content or N
The content deviates from the conditions specified in the present invention, and all are used as comparative examples.

As shown in Table 2, test numbers 2 to 4, 10, 13 to 15, 18, 2 satisfying the conditions specified by the present invention.
Nos. 0, 22, and 24 were good in both magnetic properties and surface properties of the final product. On the other hand, Test No. 1, in which the cold-rolled material had a low degree of [200] surface integration because no cold working was performed during the production of the cold-rolled material or the degree of work was inappropriate.
5, 6, 8, 9, 11, 12, 17, 19, 21, 23
And 25, the magnetic properties of the final product were not good.

FIG. 5 is a graph showing iron loss and magnetic flux density of the final product described in Table 2. In the figure, the numbers in parentheses in the figure represent steel numbers, and those with a dash in parentheses mean that the [200] plane integration of the material for cold rolling was less than 6.0. By comparing the magnetic flux densities of the products of the same steel number in FIG. 5, it is possible to clearly understand the effect of the difference in the degree of [200] plane integration of the cold rolling material on the magnetic properties.

Test No. 26 using steel 7 also had poor magnetic flux density because Fe ^* was lower than the lower limit specified in the present invention. Steel 8 whose Si equivalent exceeds the upper limit specified by the present invention 8
In Test No. 27 using No. 2, the atomic density of Fe was low, and the [200] plane integration of the material for cold rolling was high, but the magnetic flux density of the final product was low. Test No. 7 using steel 9 having an S content exceeding the upper limit specified by the present invention, and Test No. 16 using steel 10 having an N content exceeding the upper limit specified by the present invention were similarly used for the material for cold rolling. [200] The surface integration was high, but the magnetic flux density of the final product was low.

As a comparative example, in Test No. 9 in which hot-rolled sheet annealing was performed at a high temperature, the magnetic properties of the final product were not good, and a surface defect caused by abnormal grain growth occurred.

[0066]

The non-oriented electrical steel sheet of the present invention has a high atomic flux density, a high saturation magnetic flux density, and a high degree of [200] plane integration at the center of the sheet thickness. Excellent. For this reason, it is extremely useful as a core material for realizing high efficiency of motors, transformers, and the like. Also,
The cold-rolled material for a non-oriented electrical steel sheet of the present invention has a high degree of [200] plane integration at the center of the sheet thickness. By using this, a non-oriented electrical steel sheet having excellent magnetic properties and surface properties can be obtained. Can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between a random ratio of a [200] plane at a central portion of a sheet thickness of a cold rolling material and a final product.

FIG. 2 is a pole figure showing a texture at a central portion of a sheet thickness of a material for cold rolling. FIG. 2 (a) shows a steel sheet obtained by annealing a hot rolled sheet as it is, and FIG. It is a steel plate that has been processed and then annealed.

FIG. 3 is a graph showing the relationship between the degree of [200] plane integration and the degree of cold working at the center of the thickness of a cold-rolled material obtained by subjecting a hot-rolled sheet to cold working and annealing.

FIG. 4 shows a magnetic flux density B of a final product having a similar texture.
₅₀ is a graph showing a situation that varies with Fe ^* .

FIG. 5 is a graph showing the relationship between magnetic flux density and iron loss in the example.

[Explanation of symbols]

Claims (4)

[Claims] 1. The chemical composition in mass%, C: 0.005%
Hereinafter, the Si equivalent represented by the following formula is 0.1% or more;
It contains one or more members of the group consisting of Si, Al and Mn in the range of 0% or less, S: 0.030% or less, N: 0.0050% or less, and the balance is substantially from Fe. Wherein the product of the mass fraction of Fe and the density of steel is 7.40 or more, and the degree of integration of the [200] plane in the center of the sheet thickness is 1.10 or more in a random ratio. Grain-oriented electrical steel sheet; Si equivalent = Si (%) + Al (%) + 0.5Mn (%). 2. The composition of claim 1, wherein said chemical composition further comprises P:
The non-oriented electrical steel sheet according to claim 1, containing 0.05 to 0.20%. 3. A chemical composition according to claim 1 or 2, wherein the product of the mass fraction of Fe and the density of the steel is 7.40 or more;
A material for cold rolling non-oriented electrical steel sheets, characterized in that the degree of integration of the [200] plane in the central part of the sheet thickness is 6.0 or more in random ratio; Si equivalent = Si (%) + Al (% ) +0.5 Mn (%). 4. A hot rolled sheet obtained by subjecting a slab having the chemical composition according to claim 1 or 2 and having a product of the mass fraction of Fe and the density of steel to 7.40 or more to hot rolling. Rolling with rolling reduction of 4 to 15% or elongation of 0.5 to 3%
A method for producing a non-oriented electrical steel sheet, comprising: performing cold working by tensile bending, followed by annealing to obtain a cold rolling material, and performing cold rolling and finish annealing on the material.